The research program is directed toward a longitudinal appraisal of three interconnected aspects of childhood injuries among 3 cohorts of twins: I - newborn to 3 years; II - 3 years to 6 years; III - 6 years to 9 years. The three aspects pertain to: (a) behavioral- developmental features of the child's temperament, developmental competencies, deployment of attention and locus of control for injuries; (b) personality, temperament, and locus of control for the parents; and (c) structural and functional features of the family and home environment. Individual differences for children's injury liability (risk) will be considered in association with antecedent and concomitant conditions measured for the child, parents, family, and home. The study of twins also furnishes a unique opportunity to employ the co-twin control method for examining subtle conditions associated with one twin being injured more than the co-twin. The principal aims of the present program are (1) to augment assessments of the children and parents for a sample presently followed in a longitudinal study of temperament (newborn to 6 years); (2) to complete the full assessments of home environment at 6 months, 3 years, 6 years, and when there are disruptions in families at any age; (3) to assess significant events in the families that are evaluated as stressful; (4) to assess the child's and parent's view of their responsibility for health and injuries; and (5) to evaluate parental changes to modify safety practices once a child has been injured. All measures for direct and reported assessments have been developed, and for the children in Cohorts II and III, there are considerable longitudinal data available to add to the strength of the research design. An additional sample of twins will be recruited for Cohort I (children below 3 years) to increase the size of a sample presently available for assessments of child and family. The results address the developmental aspects of the types of injuries, the developmental changes in patterns among variables associated with injuries, and the joint contributions of child, parental, familial and home variables that foster higher injury risk for some children or some families. The ultimate aim of the project is to specify with more accuracy the developmental aspects of the child and the child's behavioral and material environments that can be targeted for injury control.